Hey Lenny,
There was issue with Mendix cloud for free app/sandbox
https://status.mendix.com/ here is a link when you can trace status of Mendix service, I suggest you to subscribe on it
Hi Lenny, This issue can be resolved by just publishing again. Just make a small change in the code/configuration (it can be just changing the microflow) and publish. The applicaiton will get refreshed soon.